Precoding matrix index feedback interaction with discontinuous reception

ABSTRACT

A user equipment (UE) is provided that includes a processor configured to transmit a precoding matrix index (PMI) using one of an assigned periodic PMI reporting resource that precisely aligns with the start of an on-duration of a discontinuous reception (DRX) operation mode of the UE and a first assigned periodic PMI reporting after the start of an on-duration of a discontinuous reception (DRX) operation mode of the UE.

RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 13/449,575, filed on Apr. 18, 2012, which is acontinuation of and claims priority to U.S. patent application Ser. No.12/058,448, filed on Mar. 28, 2008, which are hereby incorporated byreference in their entirety.

BACKGROUND

Easily transportable devices with wireless telecommunicationscapacities, such as mobile telephones, personal digital assistants,handheld computers, and similar devices, will be referred to herein asuser equipment (UE). The term “user equipment” may refer to a device andits associated Universal integrated Circuit Cards (UICC) that includes aSubscriber identity Module (SIM) application, a Universal SubscriberIdentity Module (USIM) application, or a Removable User Identity Module(R-UIM) application or may refer to the device itself without such acard. A UE might communicate with a second UE, some other element in atelecommunications network, an automated computing device such as aserver computer, or some other device. A communications connectionbetween a UE and another component might promote a voice call, a filetransfer, or some other type of data exchange, any of which can bereferred to as a call or a session.

As telecommunications technology has evolved, more advanced networkaccess equipment has been introduced that can provide services that werenot possible previously. This advanced network access equipment mightinclude for example, an enhanced node B (ENB) rather than a base stationor other systems and devices that are more highly evolved than theequivalent equipment in a traditional wireless telecommunicationssystem. Such advanced or next generation equipment may be referred toherein as long-term evolution (LTE) equipment. Later generation orfuture advanced equipment that designates access nodes, for examplenodes that provide radio access network (RAN) connectivity to UEs arealso referred to herein by the term ENB.

Some UEs have the capability to communicate in a packet switched mode,wherein a data stream representing a portion of a call or session isdivided into packets that are given unique identifiers. The packetsmight then be transmitted from a source to a destination along differentpaths and might arrive at the destination at different times. Uponreaching the destination, the packets are reassembled into theiroriginal sequence based on the identifiers. Voice over internet Protocol(VoIP) is a well-known system for packet switched-based voicecommunication over the Internet. The term “VoIP” will refer heron to anypacket switched voice call connected via the Internet, regardless of thespecific technology that might be used to make the call.

For a wireless VoIP call, the signal that carries data between a UE andan ENB can have a specific set of frequency, code, and time parametersand other characteristics that might be specified by the ENB. Aconnection between a UE and an ENB that has a specific set of suchcharacteristics can be referred to as a resource. An ENB typicallyestablishes a different resource for each UE with which it iscommunicating at any particular time.

New wireless communications systems may employ multiple input multipleoutput (MIMO) communication techniques. MIMO involves one or both of theUE and the ENB concurrently using multiple antennas for transmittingand/or receiving. Depending upon the radio channel conditions, themultiple antennas may be employed to increase the throughput of theradio link between the UE and the ENB, for example by transmittingindependent streams of data on each antenna, or to increase thereliability of the radio link between the UE and the ENB, for example bytransmitting redundant streams of data on the multiple antennas. Thesedifferent communications objectives may be obtained through spatialmultiplexing in the first case and through spatial diversity in thesecond case. Receiving multiple concurrent transmissions from amulti-antenna transmitter by a multi-antenna receiver may involvecomplicated processing techniques and/or algorithms.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein the referencenumerals represent like parts.

FIG. 1 is a block diagram of a telecommunications system according to anembodiment of the disclosure.

FIG. 2 is a diagram illustrating on-durations and off-durations for auser equipment according to an embodiment of the disclosure.

FIG. 3 a is an illustration of a periodic precoding matrix index (PMI)reporting resource relative to an on-duration and a retransmissionwindow associated with the on-duration according to an embodiment of thedisclosure.

FIG. 3 b is an illustration of a periodic precoding matrix indexreporting resource relative to an on-duration and a retransmissionwindow associated with the on-duration, depicting some precoding matrixindex transmissions turned off according to an embodiment of thedisclosure.

FIG. 3 c is an illustration of a periodic precoding matrix indexreporting resource relative to an on-duration and a retransmissionwindow associated with the on-duration, depicting some precoding matrixindex transmissions turned off according to an embodiment of thedisclosure.

FIG. 3 d is an illustration of a periodic precoding matrix indexreporting resource relative to an on-duration and a retransmissionwindow associated with the on-duration depicting some precoding matrixindex transmissions turned off according to an embodiment of thedisclosure.

FIG. 3 e is an illustration of a periodic precoding matrix indexreporting resource relative to an on-duration and a transmission windowassociated with the on-duration depicting some precoding matrix indextransmissions turned off according to an embodiment of the disclosure.

FIG. 3 f is an illustration of a periodic precoding matrix indexreporting resource relative to an on-duration and a retransmissionwindow associated with the on-duration, depicting some precoding matrixindex transmissions turned off according to an embodiment of thedisclosure.

FIG. 4 a is an illustration of a periodic precoding matrix indexreporting resource relative to uplink sub-frames and downlink sub-framesof an enhanced node B according to an embodiment of the disclosure.

FIG. 4 b is an illustration of a periodic precoding matrix indexreporting resource relative to an on-duration and a retransmissionwindow associated with the on-duration, depicting some precoding matrixindex transmissions turned off according to an embodiment of thedisclosure.

FIG. 5 a is an illustration of a method of transmitting precoding matrixindex control signals according to an embodiment of the disclosure.

FIG. 5 b is an illustration of another method of transmitting precodingmatrix index control signals according to an embodiment of thedisclosure.

FIG. 6 is a diagram of a wireless communications system including a userequipment operable for some of the various embodiments of thedisclosure.

FIG. 7 is a block diagram of a user equipment operable for some of thevarious embodiments of the disclosure.

FIG. 8 is a diagram of a software environment that may be implemented ona user equipment operable for some of the venous embodiments of thedisclosure.

FIG. 9 illustrates an exemplary general-purpose computer system suitablefor implementing the several embodiments of the present disclosure.

DETAILED DESCRIPTION

It should be understood at the outset that although illustrativeimplementations of one or more embodiments of the present disclosure areprovided below, the disclosed systems and/or methods may be implementedusing any number of techniques, whether currently known or in existence.The disclosure should in no way be limited to the illustrativeimplementations, drawings, and techniques illustrated below, includingthe exemplary designs and implementations illustrated and describedherein, but may be modified within the scope of the appended claimsalong with their full scope of equivalents.

In one embodiment, a user equipment (UE) is provided that includes aprocessor configured to transmit a precoding matrix index (PMI) usingone of an assigned periodic PMI reporting resource that precisely alignswith the start of an on-duration of a discontinuous reception (DRX)operation mode of the UE and a first assigned periodic PMI reportingresource after the start of an on-duration of a discontinuous reception(DRX) operation mode of the UE.

In another embodiment, a user equipment (UE) is provided that includes aprocessor configured to transmit a precoding matrix index (PMI) using afirst assigned periodic PMI reporting resource after the start of aretransmission window.

In another embodiment, a method is provided for transmitting a controlsignal from a user equipment (UE) to an enhanced node B (ENB). Themethod includes determining when an on-duration of a discontinuousreception (DRX) operation mode of the UE is scheduled. The methodincludes beginning a periodic transmission of a precoding matrix index(PMI) control signal using one of an assigned periodic PMI reportingresource that precisely aligns with the start of the on-duration and afirst assigned periodic PMI interval after the scheduled start of theon-duration.

FIG. 1 illustrates an embodiment of a wireless telecommunications system100 that includes a UE 10 capable of communicating with an ENB 20 or asimilar component. Transmissions of various types of information cantake place between the UE 10 and the ENB 20. For example, the UE 10might send the ENB 20 various types of application layer data such asVoIP data packets and data packets containing information related to webbrowsing, emailing, and other user applications, all of which may bereferred to as user plane data. Other types of information related tothe UE's application layer will be familiar to one of skill in the art.Any signal containing such information will be referred to herein as adata signal 30. Information associated with a data signal 30 will bereferred to herein as user plane data.

The UE 10 might also send the ENB 20 various types of control signalingsuch as layer 1 scheduling requests, layer 1 control signaling (CQI,PMI, NACK/ACK, etc.), high layer radio resource control (RRC) messagesand mobility measurement messages, and other control messages, all ofwhich may be referred to as control plane data, and is familiar to oneof skill in the art. The UE 10 typically generates such messages asneeded to initiate or maintain a call. Any such signal will be referredto herein as a control signal 40. Information associated with a controlsignal 40 will be referred to herein as control plane data.

Precoding matrix index (PMI) control signals and/or messages areincluded among these control signals. A PMI control signal may be amessage transmitted from the UE 10 to the ENB 20 that identifies anindex into a codebook of matrices to be employed to precode MIMO radiotransmissions. In some contexts, the PMI control signal may be referredto as PMI feedback. Precoding is an operation that the ENB 20 mayperform when transmitting to the UE 10 that may overcome certain radiochannel conditions in order to improve the MIMO signal received by theUE 10. Transmitting an index from a codebook of matrices may be moreefficient than transmitting the specific values of the precoding matrix.A matrix codebook comprises a set of matrices selected to closelyapproximate members of a much larger set of possible matrices withacceptable distortion. In some contexts, the PMI control signal may bereferred to as the PMI. In some contexts precoding may also be referredto as adapting the communication parameters or adapting parameters.

In some cases, a dedicated channel might exist between the UE 10 and theENB 20 via which control plane data may be sent. Requests to send dataon the uplink may also use this dedicated channel. This may be called ascheduling request. In other cases, a random access channel (RACH) maybe used to initiate a scheduling request. That is, in some cases, arequest for resources to send control plane data may be sent via a RACHand, in other cases, the control plane data itself might be sent via aRACH.

When the UE 10 sends a control signal 40 to the ENB 20, the ENB 20 mightreturn a response signal or other control signal to the UE 10. Forexample, if the UE 10 sends a mobility measurement message to the ENB20, the ENB 20 might respond by sending an acknowledgement message orsome other handover-related control message to the UE 10. Other types ofresponses that the ENB 20 might send upon receiving a control signal 40from the UE 10 will be familiar to one of skill in the art. Any suchresponse by the ENB 20 to a control signal 40 sent by the UE 10 will bereferred to herein as a response signal 60.

In order to save battery power, the UE 10 might periodically alternatebetween a high-power mode and a low-power mode. For example, usingtechniques known as discontinuous reception (DRX), the UE 10 mightperiodically enter short periods of relatively high power consumptionduring which data can be received. Such periods will be referred toherein as on-durations and/or active time. Between the on-durations, theUE 10 might enter longer periods in which power consumption is reducedand data is not received. Such periods will be referred to herein asoff-durations. A balance between power savings and performance can beachieved by making the off-durations as long as possible while stillkeeping the on-durations long enough for the UE 10 to properly receivedata.

The term “DRX” is used generically to refer to discontinuous reception.To avoid confusion, the terms “on-duration” and “off-duration” may alsobe used herein to refer to a UE's capability to receive data. Besidesthe on-duration, the active time defines the time that the UE is awake,which could be longer than the on-duration due to the possibleinactivity timer running which will keep the UE awake for additionaltime. Additional related discussion is found in 3^(rd) GenerationPartnership Project (3GPP) Technical Specification (TS) 36.321.

FIG. 2 illustrates an idealized View of on-durations and off-durationsfor the UE 10. On-durations 210 with higher power usage alternate intime with off-durations 220 with lower power usage. Traditionally, theUE 10 receives data only during the on-durations 210 and does notreceive data during the off-durations 220. As an example, it might bedetermined that an entire cycle of one on-duration 210 and oneoff-duration 220 should last 20 milliseconds. Of this cycle, it might bedetermined that an on-duration 210 of 5 milliseconds is sufficient forthe UE 10 to receive data without significant loss of information. Theoff-duration 220 would then last 15 milliseconds.

The determination of the sizes of the on-durations 210 and theoff-durations 220 might be based on the quality of service (QoS)parameters of an application. For example, a VoIP call might need ahigher level of quality (e.g., less delay) than an email transmission.When a call is being set up, the UE 10 and the ENB 20 enter a servicenegotiation stage in which a QoS is negotiated based on the maximumallowable delay, the maximum allowable packet loss, and similarconsiderations. The level of service to which the user of the UE 10subscribes might also be a factor in the QoS negotiations. When the QoSparameters for a call have been established, the ENB 20 sets theappropriate sizes for the on-durations 210 and the off-durations 220based on that QoS level.

Turning now to FIG. 3 a, PMI control signal transmissions are discussed.A plurality of assigned periodic PMI reporting intervals 250 are shownrelative to the on-duration duration 210 and a retransmission window230. In some contexts, the assigned periodic PMI reporting intervals 250may be referred to as assigned periodic PMI reporting resources. The PMIreporting intervals 250 depicted include a first PMI reporting internal250 a, a second PMI reporting interval 250 b, a third PMI reportinginterval 250 c, a fourth PMI reporting interval 250 d, a fifth PMIreporting interval 250 e, a sixth PMI reporting interval 250 f, aseventh PMI reporting interval 250 g, an eighth PMI reporting interval250 h, a ninth PMI reporting internal 250 l a tenth PMI reportinginterval 250 j, an eleventh PMI reporting interval 250 k, and a twelfthPMI reporting interval 250 l. It is understood that the assignedperiodic PMI reporting intervals 250 in a network is an ongoingsequence, and that many PMI reporting intervals 250 precede the firstPMI reporting interval 250 a and many PMI reporting intervals 250 followthe twelfth PMI reporting interval 250 l. In an embodiment, the UE 10may transmit PMI control signals during each PMI reporting interval 250using the assigned PMI reporting resources, as indicated in FIG. 3 a bythe solid line arrows. The retransmission window 230 provides anopportunity for the ENB 20 to retransmit data to the UE 10 that the UE10 was unable to receive properly during the on-duration 210. Note thatthe UE 10 may transmit some of the PMI control signals during the onduration 210 and the retransmission window 230. This may require thatthe UE 10 have two or more antennas with two different RF chains—a firstRF chain associated with a first antenna for receiving and a second RFchain associated with a second antenna for transmitting—so the UE 10 canreceive and transmit concurrently.

Turning now to FIG. 3 b, PMI control signal transmissions are discussedfurther. In an embodiment, it may be inefficient for the UE 10 totransmit PMI control signals on every PMI reporting interval 250.Specifically, during some of the PMI reporting intervals when the ENB 20is not transmitting to the UE 10, there may be no benefit associatedwith the UE 10 sending PMI control signals to the ENB 20, because theENB 20 need not adapt communication parameters for communicating withthe UE 10 at that time. A wide variety of techniques may be employed toreduce the transmissions of PMI control signals. As deputed in FIG. 3 bby dashed arrowed line segments, the UE 10 may turn off or stoptransmitting PMI control signals during the first PMI reporting interval250 a, the second PMI reporting interval 250 b and during the fifth PMIreporting interval 250 e through the twelfth PMI reporting interval 250l, thereby saving the power that otherwise would have been consumed bytransmitting the PMI control signals during the PMI reporting intervals250 a, 250 b, 250 e, 250 f, 250 g, 250 h, 250 i, 250 j, 250 k and 250 l.The UE 10 analyses the schedule of the on-duration 210 and determines totransmit on one of the PMI reporting intervals 250 during the first PMIreporting interval after the start of the on-duration 210 and tocontinue to transmit the PMI control signal during each successive PMIreporting interval until the end of the on-duration 210 or the end ofthe active time. The UE 10 may be instructed by the ENB 20 that itshould suspend transmitting PMI until the end of the on-duration 210 orthe end of the active time. It is understood that each of the PMIcontrol signals transmitted by the UE 10 is independent of the other PMIcontrol signals transmitted by the UE 10 and may contain new informationbased on current radio channel conditions.

Turning now to FIG. 3 c, PMI control signal transmissions are discussedfurther. In an embodiment, the UE 10 may transmit the PMI control signalduring the PMI reporting interval that immediately precedes theon-duration 210 and continues to transmit the PMI control signal duringeach successive PMI reporting interval 250 until the end of theon-duration of the end of the active time. By beginning transmitting thePMI control signal transmissions before the start of the on-duration210, the ENB 20 may be able to receive the PMI control signal from theUE 10, to process the PMI information, and to determine how to adaptcommunication parameters by the start of the on-duration 210. In somecontexts this may be referred to as resuming PMI control signaltransmissions.

Turning now to FIG. 3 d, PMI control signal transmissions are discussedfurther. In an embodiment, the UE 10 continues to periodically transmitthe PMI control signals until the retransmission window 230 has ended,than the UE 10 stops transmitting PMI control signals. The UE 10 maybegin transmitting the PMI control signal either during the first PMIreporting interval 250 of the on-duration 210, for example the third PMIreporting interval 250 c as depicted in FIG. 3 b, or during the PMIreporting interval 250 that immediately precedes the on-duration, forexample the second PMI reporting interval 250 b, as depicted in FIG. 3c. As an example, in FIG. 3 d the UE 10 is depicted as periodicallytransmitting PMI control signals from the third PMI reporting interval250 c through the eighth PMI reporting interval 250 b This scenario mayalso be described as transmitting the PMI control signal during a firstassigned periodic PMI reporting resource after the start of theon-duration 210 and transmitting the PMI control signal during eachsuccessive assigned periodic PMI reporting resource until the end of theretransmission window 230.

Turning now to FIG. 3 e, PMI control signal transmissions are discussedfurther. It may be inefficient for the UE 10 to transmit PMI controlsignals after the on-duration 210 has concluded or stopped and beforethe retransmission window 230 begins. The UE 10 analyzes the schedule ofthe on-duration 210 and may turn off or stop periodic transmissions ofthe PMI control signal after the on-duration 210 has ended or at the endof the active time. For example, as depicted in FIG. 3 e, the UE 10 mayturn on periodic transmission of PMI control signals during the thirdPMI reporting interval 250 c through the fourth PMI reporting interval250 d, turn off periodic transmission of PMI control signals during thefifth PMI reporting interval 250 e through the seventh PMI reportinginterval 250 g, turn on or resume periodic transmission of PMI controlsignals for the eighth PMI reporting interval 250 h, and then turn offperiodic transmission of PMI control signals at the ninth PMI reportinginterval 250 i. In an embodiment, the UE 10 may also transmit the PMIcontrol signal during the seventh PMI reporting interval 250 g.

Turning now to FIG. 3 f, PMI control signal transmissions are discussedfurther. In an embodiment, it may be desirable to transmit the PMIcontrol signals only during the retransmission window 230. The UE 10 maybegin transmitting the PMI control signal with the first PMI reportinginterval 250 in the retransmission window 230 or with the PMI reportinginterval 250 that immediately precedes the retransmission window 230 andto transmit PMI control signals during each successive PMI reportinginterval 250 until the end of the retransmission window 230.

One will readily appreciate that the several PMI control signaltransmission scenarios admit of a variety of related combinations andextensions along the lines of the description above. All of thesecombinations and extensions are contemplated by the present disclosure.Additional technical details related to discontinuous reception (DRX)operation modes and assigned periodic precoding matrix indicatorreporting resources may be found in TS 36.300 and TS 36.321 both ofwhich are hereby incorporated herein by reference for all purposes.

Turning now to FIG. 4 a, the timing relationship between the PMIreporting intervals 250 and a plurality of uplink sub-frames anddownlink sub-frames of an ENB is discussed. In a practical wirelessnetwork a number of time lags are observed between the UE 10transmitting the PMI control signal and the ENB 20 adapting thecommunication parameters based on the PMI control signals. A propagationdelay is introduced by the time it takes for the radio frequency signalemitted by the UE 10 containing the PMI control signal to propagatethrough the radio channel to the ENB 20. The ENB 20 processing issegmented into uplink sub-frames 260 and downlink sub-frames 270, forexample a first uplink sub-frame 260 a, a second uplink sub-frame 260 b,a third uplink sub-frame 260 c, a first downlink sub-frame 270 a, asecond downlink sub-frame 270 b, and a third downlink sub-frame 270 c.The timing of the uplink sub-frame 260 edges and the downlink sub-frame270 edges may not align due to the propagation delay and/or oscillatordrift between the UE 10 and the ENB 20. As an example, the PMI controlsignal transmitted during the third PMI reporting interval 250 c may bereceived by the ENB 20 in the first uplink sub-frame 260 a, processed bythe ENB 20 to adapt communication parameters in the second uplink,sub-frame 260 b, and the newly adapted communication parameters may beemployed by the ENB 20 for communicating with the UE 10 during the thirddownlink sub-frame 270 c. In an embodiment, the best case sub-framedelay is about two sub-frames. In another embodiment, the sub-framedelay may be about three sub-frames or about four sub-frames.

Turning now to FIG. 4 b, PMI control signal transmissions are discussedfurther. In an embodiment, the UE 10 takes the time lags discussed abovewith reference to FIG. 4 a into account in determining when to beginperiodic transmission of the PMI control signal before the on-duration210 and before the retransmission window 230. As an example, as depletedin FIG. 4 b, beginning periodic transmission of the PMI control signalwith the third PMI reporting interval 250 c may not provide enough leadtime for the ENB 20 to receive, process, and adapt communicationparameters by the beginning of the on-duration 210. If the UE 10 beganperiodic transmission of the PMI control signal with the third PMIreporting interval, the first downlink sub-frame and also possibly thesecond downlink sub-frame may not benefit from adaptation based on afresh PMI control signal and less efficient communication operationbetween the UE 10 and the ENB 20 may result. For example, the ENB 20 mayuse the previously transmitted PMI control signal that indexes to aprecoding matrix that does not suit the current radio channel andexcessive distortion may result. The excessive distortion may cause theUE 10 to fail to receive one or more data packets, for example, and theENB 20 may need to retransmit the data packets using HARQ, possiblydecreasing the throughput of the radio channel and increasing the UE 10power consumption for waking up to listen to the retransmissions.

As depicted, the UE 10 begins periodic transmission of PMI controlsignals with the second PMI reporting interval 250 b, thereby providingenough time to permit the ENB 20 to receive the PMI control signal,process the PMI control signal, and adapt communication parameters bythe start of the on-duration 210. Similarly, the UE 10 may determinewhen to start or resume periodic transmission of the PMI control signalbefore the retransmission window 230 taking into account the time neededby the ENB 20 to receive the PMI control signal, process the PMI controlsignal, and adapt communication parameters by the start of theretransmission window 230. The ENB 20 may instruct the UE 10 how todetermine when to start or resume periodic transmission of the PMIcontrol signal before the retransmission window 230.

Turning now to FIG. 5 a, a method 300 of the UE 10 for controlling PMIcontrol signal transmissions is discussed. At block 305, the UE 10determines when the next on-duration 210 is scheduled. The ENB 20 mayinstruct the UE 10 to begin this process. At block 310, the UE 10determines when the retransmission window 230 associated with theon-duration 210 is scheduled to end. In block 315, the UE 10 identifiesor selects a PMI reporting interval 250 that precedes the start of theon-duration 210. In an embodiment, the UE 10 may select any PMIreporting interval 250 that precedes the start of the on-duration 210.In another embodiment, the UE 10 may select the PMI reporting interval250 that immediately precedes the start of the on-duration 210. Anotherway of describing the behavior of this embodiment is that the UE 10 mayselect the last PMI reporting interval 250 that occurs before the startof the on-duration 210. In another embodiment the UE 10 takes intoaccount the time lags of radio frequency signal propagation, timingoffsets associated with oscillator drifts, and processing by the ENB 20to select the PMI reporting interval 250 that precedes the on-duration210. In an embodiment, the UE 10 may estimate the time lags to consumeabout a time duration of two sub-frames. In another embodiment the UE 10may estimate the time lags to consume about a time duration of threesub-frames or four sub-frames. In some circumstances, depending ontiming alignments between the on-duration 210, the UE 10 may select thetest PMI reporting interval 250 that occurs before the start of theon-duration 210 or the UE 10 may select the next to the last PMIreporting interval 250 that occurs before the start of the on-duration210. In another embodiment, however, the UE 10 may select the first PMIreporting interval after the start of the on-duration 210. The UE 10 mayselect the first PMI interval as the precise start of the on-duration210, when the PMI reporting interval 250 precisely aligns with the startof the on-duration 210.

At block 320, the UE 10 transmits the PMI control signal on the selectedPMI reporting interval 250. In an embodiment, the processing of block320 may include a waiting process or a sleeping process wherein theprocess 300 only executes block 320 at the appropriate time, for exampleat the time of the selected PMI reporting interval 250. At block 325, ifthe retransmission window 230 associated with the on-duration 210 hasnot been completed, the process 300 returns to block 320. By loopingthrough blocks 320 and 325, the UE 10 periodically transmits the PMIcontrol signal to the ENB 20. In an embodiment, it is understood thatthe UE 10 re-determines the PMI values and/or information for each newtransmission of the PMI control signal. It is also understood that theUE 10 transmits the PMI control signal at about the assigned time of thePMI reporting interval 250 over assigned PMI reporting resources.

At block 325, if the retransmission window 230 associated with theon-duration 210 has completed, the processing returns to block 305. Thiscan be understood to include stopping periodic transmission of PMIcontrol signals until the method 300 returns to block 320.

Turning now to FIG. 5 b, a method 350 of the UE 10 for controlling PMIcontrol signal transmissions is discussed. At block 355, the UE 10determines when the next on-duration 210 is scheduled to begin and toend. At block 360, the UE 10 determines when the retransmission window230 associated with the next on-duration 210 is scheduled to begin andend. In block 365, the UE 10 identifies or selects the PMI reportinginterval that precedes the next scheduled en-duration 210 to startperiodic PMI control signal transmissions. As described with respect toblock 315 above, the UE 10 may select the PMI reporting intervalaccording to several different selection criteria, all of which are alsocontemplated by the method 350.

At block 370, the UE 10 transmits the PMI control signal on the selectedPMI reporting interval 250. In an embodiment, the processing of block370 may include a waiting process or a sleeping process wherein theprocess 350 only executes block 370 at the appropriate time, for exampleat the time of the selected PMI reporting interval 250. At block 375, ifthe on-duration 210 has not completed, the method 350 returns to block370. By looping through blocks 370 and 375, the UE 10 periodicallytransmits the PMI control signal to the ENB 20. In an embodiment, it isunderstood that the UE 10 re-determines the PMI values and/orinformation for each new transmission of the PMI control signal. It isalso understood that the UE 10 transmits the PMI control signal at aboutthe assigned time of the PMI reporting interval 250 over assigned PMIreporting resources.

At block 375, if the on-duration 210 has completed, the processingproceeds to block 380. At block 380, the UE 10 identifies or selects thePMI reporting interval that precedes the retransmission window 230 tostart or resume periodic PMI control signal transmissions. As describedwith respect to block 315 above, the UE 10 may select the PMI reportinginterval according to several different selection criteria, all of whichare also contemplated by method 350. In another embodiment, however,after on-duration 210 has completed the method 350 may complete and noPMI control signals may be transmitted during the retransmission window230.

At block 385, the UE 10 transmits the PMI control signal on the selectedPMI repotting interval 250. In an embodiment, the processing of block385 may include a waiting process or a sleeping process wherein theprocess 350 only executes block 385 at the appropriate time, for exampleat the time of the selected PMI reporting interval 250. At block 390, ifthe retransmission window 230 has not completed, the method 350 returnsto block 385. By looping through blocks 385 and 390, the UE 10periodically transmits the PMI control signal to the ENB 20. In anembodiment, it is understood that the UE 10 re-determines the PMI valuesand/or information for each new transmission of the PMI control signal.It is also understood that the UE 10 transmits the PMI control signal atabout the assigned time of the PMI reporting interval 250 over assignedPMI reporting resources.

At block 390, if the retransmission window 230 has completed, theprocessing returns to block 355. This can be understood to includestopping periodic transmission of PMI control signals until the method350 returns to block 370.

FIG. 6 illustrates a wireless communications system including anembodiment of the UE 10. The UE 10 is operable for implementing aspectsof the disclosure, but the disclosure should not be limited to theseimplementations. Though illustrated as a mobile phone, the UE 10 maytake various forms including a wireless handset, a pager, a personaldigital assistant (PDA), a portable computer, a tablet computer, or alaptop computer. Many suitable devices combine some or all of thesefunctions. In some embodiments of the disclosure, the UE 10 is not ageneral purpose computing device like a portable, laptop or tabletcomputer, but rather is a special-purpose communications device such asa mobile phone, a wireless handset, a pager, a PDA, or atelecommunications device installed in a vehicle. In another embodiment,the UE 10 may be a portable, laptop or other computing device. The UE 10may support specialized activities such as gaming, inventory control,job control and/or task management functions, and so on.

The UE 10 includes a display 402. In an embodiment, the UE 10 includestwo antennas 403—a first antenna 403A and a second antenna 403B—whichmay be used for MIMO operations. The two antennas 403 may also permitthe UE 10 to transmit the PMI control signals during the on-duration 210and/or during the retransmission window 230 on the first antenna 403Awhile concurrently receiving signals sent by the ENB 20 to the UE 10 onthe second antenna 403B. The UE 10 also includes a touch-sensitivesurface, a key board or other input keys generally referred as 404 forinput by a user. The keyboard may be a full or reduced alphanumerickeyboard such as QWERTY, Dvorak, AZERTY, and sequential types, or atraditional numeric keypad with alphabet letters associated with atelephone keypad. The input keys may include a trackwheel, an exit orescape key, a trackball and other navigational or functional keys, whichmay be inwardly depressed to provide fodder input function. The UE 10may present options for the user to select, controls for the user toactuate, end/or cursors or other indicators for the user to direct.

The UE 10 may further accept date entry from the user, including numbersto dial or various parameter values for configuring the operation of theUE 10. The UE 10 may further execute one or more software or firmwareapplications in response to user commands. These applications mayconfigure the UE 10 to perform various customized functions in responseto user interaction. Additionally, the UE 10 may be programmed and/orconfigured over-the-air, for example from a wireless base station, awireless access point, or a peer UE 10.

Among the various applications executable by the UE 10 are a webbrowser, which enables the display 402 to show a web page. The web pagemay be obtained via wireless communications with a wireless networkaccess node, a cell tower, a peer UE 10, or any other wirelesscommunication network or system 400. The network 400 is coupled to awired network 408, such as the Internet. Via the wireless link and thewired network, the UE 10 has access to information on various serverssuch as a server 410. The server 410 may provide content that may beshown on the display 402. Alternately, the UE 10 may access the network400 through a peer UE 10 acting as an intermediary, in a relay type orhop type of connection.

FIG. 7 shows a block diagram of the UE 10. While a variety of knowncomponents of UEs 10 are depicted, in an embodiment a subset of thelisted components and/or additional components not listed may beincluded in the UE 10. The UE 10 includes a digital signal processor(DSP) 502 and a memory 504. As shown, the UE 10 may further include afront end unit 506, a radio frequency (RF) transceiver 508, an analogbaseband processing unit 510, a microphone 512, an earpiece speaker 514,a headset port 516, an input/output interface 518, a removable memorycard 520, a universal serial bus (USB) port 522, a short range wirelesscommunication sub-system 524, an alert 526, a keypad 528, a liquidcrystal display (LCD), which may include a touch sensitive surface 530,an LCD controller 532, a charge-coupled device (CCD) camera 534, acamera controller 536, and a global positioning system (GPS) sensor 538.In an embodiment, the UE 10 may include another kind of display thatdoes not provide a tough sensitive screen. In an embodiment, the DSP 502may communicate directly with the memory 504 without passing through theinput/output interface 518.

In one embodiment, the front end unit 506 interfaces with the twoantennas 403 and may comprise one receive chain and one transmit chain.One antenna 403 is for transmitting and the other antenna 403 is forreceiving. This allows the UE 10 to transmit the PMI signals at the sametime it is receiving control and/or data information from the ENB 20.

The DSP 502 or some other form of controller or central processing unitoperates to control the various components of the UE 10 in accordancewith embedded software or firmware stored in memory 504 or stored inmemory contained within the DSP 502 itself. In addition to the embeddedsoftware or firmware, the DSP 502 may execute other applications storedin the memory 504 or made available via information carrier media suchas portable data storage media like the removable memory card 520 or viawired or wireless network communications. The application software maycomprise a compiled set of machine-readable instructions that configurethe DSP 502 to provide the desired functionality, or the applicationsoftware may be high-level software instructions to be processed by aninterpreter or compiler to indirectly configure the DSP 502.

The antenna and front end unit 506 may be provided to convert betweenwireless signals and electrical signals, enabling the UE 10 to send andreceive information from a cellular network or some other availablewireless communications network or from a peer UE 10. In an embodiment,the antenna and front end unit 506 may include multiple antennas tosupport beam forming and/or multiple input multiple output (MIMO)operations. As is known to those skilled in the art, MIMO operations mayprovide spatial diversity which can be used to overcome difficultchannel conditions and/or increase channel throughput. The antenna andfront end unit 506 may include antenna tuning and/or impedance matchingcomponents. RF power amplifiers, and/or low noise amplifiers.

The RF transceiver 508 provides frequency shifting, converting receivedRF signals to baseband and converting baseband transmit signals to RF.In some descriptions a radio transceiver or RF transceiver may beunderstood to include other signal processing functionality such asmodulation/demodulation, coding/decoding, interleaving/deinterleaving,spreading/despreading, inverse fast Fourier transforming (IFFT)/fastFourier transforming (FFT), cyclic prefix appending/removal, and othersignal processing functions. For the purposes of clarity, thedescription here separates the description of this signal processingfrom the RF and/or radio stage and conceptually allocates that signalprocessing to the analog baseband processing unit 510 and/or the DSP 502or other central processing unit. In some embodiments, the RFTransceiver 508, portions of the Antenna and Front End 506, and theanalog baseband processing unit 510 may be combined in one or moreprocessing units and/or application specific integrated circuits(ASICs).

The analog baseband processing unit 510 may provide various analogprocessing of inputs and outputs, for example analog processing ofinputs from the microphone 512 and the headset 516 and outputs to theearpiece 514 and the headset 516. To that end, the analog basebandprocessing unit 510 may have ports for connecting to the built-inmicrophone 512 and the earpiece speaker 514 that enable the UE 10 to beused as a cell phone. The analog baseband processing unit 510 mayfurther include a port for connecting to a headset or other hands-freemicrophone and speaker configuration. The analog baseband processingunit 510 may provide digital-to-analog conversion in one signaldirection and analog-to-digital conversion in the opposing signaldirection. In some embodiments, at least some of the functionality ofthe analog baseband processing unit 510 may be provided by digitalprocessing components, for example by the DSP 502 or by other centralprocessing units.

The DSP 502 may perform modulation/demodulation, coding/decoding,interleaving/deinterleaving, spreading/despreading, inverse fast Fouriertransforming (IFFT)/fast Fourier transforming (FFT), cyclic prefixappending/removal, and other signal processing functions associated withwireless communications. In an embodiment, for example in a codedivision multiple access (CDMA) technology application, for atransmitter function the DSP 502 may perform modulation, coding,interleaving, and spreading, and for a receiver function the DSP 502 mayperform despreading, deinterleaving, decoding, and demodulation. Inanother embodiment, for example in an orthogonal frequency divisionmultiplex-access (OFDMA) technology application, for the transmitterfunction the DSP 502 may perform modulation, coding, interleaving,diverse fast Fourier transforming, and cyclic prefix appending, and fora receiver function the DSP 502 may perform cyclic prefix removal, fastFourier transforming, deinterleaving, decoding, and demodulation. Inother wireless technology applications, yet other signal processingfunctions and combinations of signal processing functions may beperformed by the DSP 502.

The DSP 502 may communicate with a wireless network via the analogbaseband processing unit 510. In some embodiments, the communication mayprovide Internet connectivity, enabling a user to gain access to contenton the Internet and to send and receive e-mail or text messages. Theinput/output interface 518 interconnects the DSP 502 and variousmemories and interfaces. The memory 504 and the removable memory card520 may provide software and data to configure the operation of the DSP502. Among the interfaces may be the USB interface 522 and the shortrange wireless communication sub-system 524. The USB interface 522 maybe used to charge the UE 10 and may also enable the UE 10 to function asa peripheral device to exchange information with a personal computer orother computer system. The short range wireless communication sub-system524 may include an infrared port, a Bluetooth interface, an IEEE 802.11compliant wireless interface, or any other short range wirelesscommunication sub-system, which may enable the UE 10 to communicatewirelessly with other nearby mobile devices and/or wireless basestations.

The input/output interface 518 may further connect the DSP 502 to thealert 526 that, when triggered, causes the UE 10 to provide a notice tothe user, for example, by ringing, playing a melody, or vibrating. Thealert 526 may serve as a mechanism for alerting the user to any ofvarious events such as an incoming call, a new text message, and anappointment reminder by silently vibrating, or by playing a specific preassigned melody for a particular caller.

The keypad 528 couples to the DSP 502 via the Interface 518 to provideone mechanism for the user to make selections, enter information, andotherwise provide input to the UE 10. The keyboard 528 may be a full orreduced alphanumeric keyboard such as QWERTY, Dvorak, AZERTY andsequential types, or a traditional numeric keypad with alphabet lettersassociated with a telephone keypad. The input keys may include atrackwheel, an exit or escape key, a trackball, and other navigationalor functional keys, which may be inwardly depressed to provide furtherinput function. Another input mechanism may be the LCD 530, which mayinclude touch screen capability and also display text and/or graphics tothe user. The LCD controller 532 couples the DSP 502 to the LCD 530.

The CCD camera 534, if equipped, enables the UE 10 to take digitalpictures. The DSP 502 communicates with the CCD camera 534 via thecamera controller 536. In another embodiment, a camera operatingaccording to a technology other than Charge Coupled Device cameras maybe employed. The GPS sensor 538 is coupled to the DSP 502 to decodeglobal positioning system signals, thereby enabling the UE 10 todetermine its position. Various other peripherals may also be includedto provide additional functions, e.g., radio and television reception.

FIG. 8 illustrates a software environment 602 that may be implemented bythe DSP 502. The DSP 502 executes operating system drivers 604 thatprovide a platform from which the rest of the software operates. Theoperating system drivers 604 provide drivers for the wireless devicehardware with standardized interfaces that are accessible to applicationsoftware. The operating system drivers 604 include applicationmanagement services (“AMS”) 606 that transfer control betweenapplications running on the UE 10. Also shown in FIG. 8 are a webbrowser application 608, a media player application 610, and Javaapplets 612. The web browser application 608 configures the UE 10 tooperate as a web browser, allowing a user to enter information intoforms and select links to retrieve and view web pages. The media playerapplication 610 configures the UE 10 to retrieve and play audio oraudiovisual media. The Java applets 612 configures the UE 10 to providegames, utilities, and other functionality. A component 614 might providefunctionality related to PMI feedback interaction as described herein.Although the component 614 is shown in FIG. 8 at an application softwarelevel, the component 614 may be implemented at a lower system level thanis illustrated in FIG. 8.

Some aspects of the system 100 described above may be implemented on anygeneral-purpose computer with sufficient processing power, memoryresources, and network throughput capability to handle the necessaryworkload placed upon it. FIG. 9 illustrates a typical, general-purposecomputer system suitable for implementing aspects of one or moreembodiments disclosed herein. The computer system 660 includes aprocessor 682 (which may be referred to as a central processor unit orCPU) that is in communication with memory devices including secondarystorage 684, read only memory (ROM) 686, random access memory (RAM) 688,input/output (I/O) devices 690, and network connectivity devices 692.The processor 682 may be implemented as one or more CPU chips.

The secondary storage 684 is typically comprised of one or more diskdrives or tape drives and is used for non-volatile storage of data andas an over-flow data storage device if RAM 688 is not large enough tohold all working data. Secondary storage 684 may be used to storeprograms which are loaded into RAM 688 when such programs are selectedfor execution. The ROM 688 is used to store instructions and perhapsdata which are read during program execution. ROM 686 is a non-volatilememory device which typically has a small memory capacity relative tothe larger memory capacity of secondary storage. The RAM 688 is used tostore volatile data and perhaps to store instructions. Access to bothROM 686 and RAM 688 is typically faster than to secondary storage 684.

I/O devices 690 may include printers, video monitors, liquid crystaldisplays (LCDs), touch screen displays, keyboards, keypads, switches,dials, mice, track balls, voice recognizers, card readers, paper tapereaders, or other well-known input devices.

The network connectivity devices 692 may take the form of modems, modembanks, ethernet cards, universal serial bus (USB) interface cards,serial interfaces, token ring cards, fiber distributed data interface(FDDI) cards, wireless local area network (WLAN) cards, radiotransceiver cards such as code division multiple access (CDMA) and/orglobal system for mobile communications (GSM) radio transceiver cards,and other well-known network devices. These network connectivity devices602 may enable the processor 682 to communicate with an Internet or oneor more intranets. With such a network connection, it is contemplatedthat the processor 682 might receive information from the network, ormight output information to the network in the course of performing theabove-described method steps. Such information, which is oftenrepresented as a sequence of instructions to be executed using processor682, may be received from and outputted to the network, for example, inthe form of a computer data signal embodied in a carrier wave. Thenetwork connectivity devices 692 may also include one or moretransmitter and receivers for wirelessly or otherwise transmitting andreceiving signal as are well know to one of ordinary skill in the art.

Such information, which may include data or instructions to be executedusing processor 682 for example, may be received from and outputted tothe network, for example, in the form of a computer data baseband signalor signal embodied in a carrier wave. The baseband signal or signalembodied in the carrier wave generated by the network connectivitydevices 692 may propagate in or on the surface of electrical conductors,in coaxial cables, in waveguides, in optical media, for example opticalfiber, or in the air or free space. The information contained in thebaseband signal or signal embedded to the carrier wave may be orderedaccording to different sequences, as may be desirable for eitherprocessing or generating the information or transmitting or receivingthe information. The baseband signal or signal embedded in the carrierwave, or other types of signals currently used or hereafter developed,referred to herein as the transmission medium, may be generatedaccording to several methods well known to one skilled in the art.

The processor 682 executes instructions, codes, computer programs,scripts which it accesses from hard disk, floppy disk, optical disk(these various disk based systems may all be considered secondarystorage 684), ROM 686, RAM 688, or the network connectivity devices 692.While only one processor 682 is shown, multiple processors may bepresent. Thus, while instructions may be discussed as executed by aprocessor, the instructions may be executed simultaneously, serially, orotherwise executed by one or multiple processors.

While several embodiments have been provided in the present disclosure,if should be understood that the disclosed systems and methods may beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given heroin. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted, or not implemented.

Also, techniques, systems, subsystems and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component, whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and could be made without departing scorn the spirit and scopedisclosed herein.

What is claimed is:
 1. A user equipment (UE), comprising: a transmitter;a receiver; and one or more processors configured to: receive, using thereceiver, a resource configuration, the resource configurationindicating a periodic reporting resource for transmitting precodingmatrix indexes (PMIs); control the receiver in the UE to have an activetime, wherein the active time includes at least a time periodcorresponding to an on duration and a time period when an inactivitytimer is running; control the transmitter to transmit a PMI using thePMI reporting resource that immediately follows the on duration; andcontrol the transmitter to not transmit PMIS when not in the activetime.
 2. The UE of claim 1, wherein the one or more processors furtherconfigured to identify one or more reporting resources for transmittingPMIs using the periodic PMI reporting resource, wherein the one or moreidentified reporting resources occur during the active time.
 3. The UEof claim 1, wherein the active time is associated with a discontinuousreception (DRX) cycle.
 4. The UE of claim 3, wherein the active timeincludes a periodic on-duration, the periodic on-duration associatedwith DRX operation mode of the UE.
 5. The UE of claim 3, wherein theactive time includes a retransmission window.
 6. The UE of claim 1, theone or more processors further configured to control the transmitter totransmit a PMI using the PMI reporting resource that immediatelyprecedes the on duration.
 7. A method for user equipment (UE) includinga receiver and a transmitter, comprising: receiving using the receiver,a resource configuration, the resource configuration indicating aperiodic reporting resource for transmitting precoding matrix indices(PMIs); controlling the receiver in the UE to have an active time,wherein the active time includes at least a time period corresponding toan on duration and a time period when an inactivity timer is running;controlling the transmitter to transmit an PMI using the PMI reportingresource that immediately follows the on duration; and controlling thetransmitter to not transmit PMIs when not in the active time.
 8. Themethod of claim 7, further comprising identifying one or more reportingresources for transmitting the PMI using the periodic PMI reportingresource, wherein the one or more identified reporting resources occurduring the active time.
 9. The method of claim 7, wherein the activetime is associated with a discontinuous reception (DRX) cycle.
 10. Themethod of claim 7, wherein the active time includes a retransmissionwindow.
 11. The method of claim 7, further comprising controlling thetransmitter to transmit a PMI using the PMI reporting resource thatimmediately precedes the on duration.